Drill pipe steel grades typically include E75, X95, G105, S135, and V150. Drill pipe is a steel pipe with a thread at the end, used to connect the surface equipment of the drilling rig to the drilling and grinding equipment or bottom hole device at the bottom of the drilling well. Tools commonly used in oil, natural gas and geological exploration projects are the key materials for connecting drill bits and drilling tools. Drill pipes With different drilling depths and complexities, drill pipes of different materials and steel grades need to be used to meet drilling requirements.

What is drill pipe made of? 

Drill pipes conforming to API Spec 5DP standards are typically made of:
High-quality seamless pipe;
Temperature treatment (quenching + tempering);
Connected with a high-strength friction-welded tool joint.

The core design objectives are:
High yield strength;
High fatigue life;
Good torsional and corrosion resistance.

Classification method of drill pipe steel grades

The steel grade classification of drill pipes mainly adopts API specifications (American Petroleum Institute) standards. API specifications stipulate the size, hardness, material composition and other standards of drill pipe to facilitate the drilling team to select appropriate drill pipe in different geological environments.

API Spec 5DP specifies: 

Drill pipe steel grade = Minimum yield strength (ksi) + letter designation
Number: Indicates minimum yield strength (ksi)
Letter: Indicates steel grade designation
Unit: 1 ksi = 1000 psi

For example:

E75 → Minimum yield strength ≥ 75 ksi (75,000 psi)
S135 → Minimum yield strength ≥ 135 ksi (135,000 psi)

E75, X95, G105, and S135 are all official API Spec 5DP standard steel grades. V150 is a non-API standard high-strength steel grade, mostly customized or internal control standard products.

Drill pipe steel grade classification 

The steel grades of commonly used drill pipes can be divided into the following five types:

1. E75 drill pipe

It is a relatively common steel grade for drill pipes. It is mainly composed of carbon, manganese, silicon, phosphorus, sulfur, chromium, molybdenum and other elements. It has high strength and toughness.

2. X95 drill pipe

It is a high-strength drill pipe steel grade, mainly composed of chromium, molybdenum, titanium and other elements. It has extremely high wear resistance and corrosion resistance, and is suitable for deep and difficult drilling operations.

3. G105 drill pipe

It is a drill pipe steel grade with good wear resistance. It is mainly composed of chromium, molybdenum, nickel and other elements. It has high strength and toughness and is suitable for borehole wall drilling in deep and ultra-deep wells. mechanical.

4. S135 drill pipe

It is a high-strength, high-toughness, high-wear-resistant drill pipe steel grade. It is mainly composed of carbon, molybdenum, chromium and other elements. It can adapt to extreme underground environments and can meet the needs of ultra-deep and high-strength applications. well requirements.

5. V150 drill pipe

It is a new type of steel grade composed of vanadium, phosphorus, sulfur and other elements. It has high strength, high rigidity and high wear resistance, and is widely used in new and difficult drilling fields.

Drill pipe material grades

The drill pipe grade defines the minimum yield strength and specifies the material property requirements:

Material Grade	Yield Strength (psi)	Tensile Strength (psi)
E-75	75000-105000	100000
X-95	95000-125000	105000
G-105	105000-135000	115000
S-135	135000-165000	145000

Drill pipe grade identification

Drill pipe grade markings are located on the tool joint or bottom pin, in the following format:
Manufacturer Symbol / Welding Month / Welding Year / Drill Pipe Grade
Example: AA / 12 / 23 / S135

How to identify drill pipe grade?

1. Observe the drill pipe steel grade markings to determine the steel grade and strength grade.

2. Infer the drill pipe steel grade by testing and analyzing its chemical composition. For example, drill pipes with high chromium, high molybdenum, and high titanium content may belong to the high-strength G-105 or S-135 grade.

3. Perform mechanical property tests on the drill pipe, such as tensile and impact tests, to determine its strength grade and steel grade.

How to choose the appropriate drill pipe steel grade

When selecting drill pipe steel grade, consider the following points:

1. Well depth and complexity

Select the appropriate drill pipe steel grade according to factors such as drilling depth, wellbore size, inclination angle, and formation status to meet the requirements of drilling construction.

2. Underground environment

Select drill pipe materials that can adapt to the underground environment, including the effects of ambient temperature, pressure, corrosive agents, etc.

3. Cost factors

The performance of drill pipe steel grade is directly related to the price. Select the appropriate steel grade to reduce the cost as much as possible while ensuring safety and operating efficiency.

FAQ

1. What risks can arise from incorrect drill pipe steel grade selection?

Drill pipe breakage;
Torque failure;
Fatigue cracking;
Downhole accidents and well shutdown losses.
Therefore, steel grade selection is a critical step in drilling design.

2. Is a higher drill pipe steel grade always better?

Not necessarily.
Higher drill pipe steel grades offer greater strength, but also require higher impact resistance, cost, and fatigue characteristics. Using excessively high steel grades under low-stress conditions may actually increase costs and reduce economic efficiency.

Summarize

The steel grade of drill pipe is one of the key factors that affects drilling operations. Each steel grade has its own characteristics. The steel grade classification of drill pipe is very critical. Choosing the appropriate steel grade is of great significance to drilling operations. When selecting, it is necessary to fully consider factors such as the safety, efficiency, and economy of drilling operations. Through reasonable selection of drill pipe steel grades, the effectiveness and efficiency of drilling operations can be improved, and the risk of accidents can be reduced.

Read more: Calculation of The Internal Capacity of Drill Pipes or Size of Drill Pipe